/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
using System;
using java = biz.ritter.javapi;

using org.apache.commons.codec;
using org.apache.commons.codec.binary;

namespace org.apache.commons.codec.digest
{

    /**
     * Operations to simplifiy common {@link java.security.MessageDigest} tasks. This class is thread safe.
     * 
     * @author Apache Software Foundation
     * @version $Id: DigestUtils.java 801391 2009-08-05 19:55:54Z ggregory $
     */
    public class DigestUtils
    {

        private static readonly int STREAM_BUFFER_LENGTH = 1024;

        /**
         * Read through an InputStream and returns the digest for the data
         * 
         * @param digest
         *            The MessageDigest to use (e.g. MD5)
         * @param data
         *            Data to digest
         * @return MD5 digest
         * @throws IOException
         *             On error reading from the stream
         */
        private static byte[] digest(java.security.MessageDigest digest, java.io.InputStream data)
        {//throws IOException {
            byte[] buffer = new byte[STREAM_BUFFER_LENGTH];
            int read = data.read(buffer, 0, STREAM_BUFFER_LENGTH);

            while (read > -1)
            {
                digest.update(buffer, 0, read);
                read = data.read(buffer, 0, STREAM_BUFFER_LENGTH);
            }

            return digest.digest();
        }

        /**
         * Calls {@link StringUtils#getBytesUtf8(String)}
         * 
         * @param string
         *            the String to encode
         * @return encoded bytes
         */
        private static byte[] getBytesUtf8(String data)
        {
            return StringUtils.getBytesUtf8(data);
        }

        /**
         * Returns a <code>MessageDigest</code> for the given <code>algorithm</code>.
         * 
         * @param algorithm
         *            the name of the algorithm requested. See <a
         *            href="http://java.sun.com/j2se/1.3/docs/guide/security/CryptoSpec.html#AppA">Appendix A in the Java
         *            Cryptography Architecture API Specification & Reference</a> for information about standard algorithm
         *            names.
         * @return An MD5 digest instance.
         * @see MessageDigest#getInstance(String)
         * @throws RuntimeException
         *             when a {@link java.security.NoSuchAlgorithmException} is caught.
         */
        static java.security.MessageDigest getDigest(String algorithm)
        {
            try
            {
                return java.security.MessageDigest.getInstance(algorithm);
            }
            catch (java.security.NoSuchAlgorithmException e)
            {
                throw new java.lang.RuntimeException(e.getMessage());
            }
        }

        /**
         * Returns an MD5 MessageDigest.
         * 
         * @return An MD5 digest instance.
         * @throws RuntimeException
         *             when a {@link java.security.NoSuchAlgorithmException} is caught.
         */
        private static java.security.MessageDigest getMd5Digest()
        {
            return getDigest("MD5");
        }

        /**
         * Returns an SHA-256 digest.
         * <p>
         * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
         * </p>
         * 
         * @return An SHA-256 digest instance.
         * @throws RuntimeException
         *             when a {@link java.security.NoSuchAlgorithmException} is caught.
         */
        private static java.security.MessageDigest getSha256Digest()
        {
            return getDigest("SHA-256");
        }

        /**
         * Returns an SHA-384 digest.
         * <p>
         * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
         * </p>
         * 
         * @return An SHA-384 digest instance.
         * @throws RuntimeException
         *             when a {@link java.security.NoSuchAlgorithmException} is caught.
         */
        private static java.security.MessageDigest getSha384Digest()
        {
            return getDigest("SHA-384");
        }

        /**
         * Returns an SHA-512 digest.
         * <p>
         * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
         * </p>
         * 
         * @return An SHA-512 digest instance.
         * @throws RuntimeException
         *             when a {@link java.security.NoSuchAlgorithmException} is caught.
         */
        private static java.security.MessageDigest getSha512Digest()
        {
            return getDigest("SHA-512");
        }

        /**
         * Returns an SHA-1 digest.
         * 
         * @return An SHA-1 digest instance.
         * @throws RuntimeException
         *             when a {@link java.security.NoSuchAlgorithmException} is caught.
         */
        private static java.security.MessageDigest getShaDigest()
        {
            return getDigest("SHA");
        }

        /**
         * Calculates the MD5 digest and returns the value as a 16 element <code>byte[]</code>.
         * 
         * @param data
         *            Data to digest
         * @return MD5 digest
         */
        public static byte[] md5(byte[] data)
        {
            return getMd5Digest().digest(data);
        }

        /**
         * Calculates the MD5 digest and returns the value as a 16 element <code>byte[]</code>.
         * 
         * @param data
         *            Data to digest
         * @return MD5 digest
         * @throws IOException
         *             On error reading from the stream
         * @since 1.4
         */
        public static byte[] md5(java.io.InputStream data)
        {// throws IOException {
            return digest(getMd5Digest(), data);
        }

        /**
         * Calculates the MD5 digest and returns the value as a 16 element <code>byte[]</code>.
         * 
         * @param data
         *            Data to digest
         * @return MD5 digest
         */
        public static byte[] md5(String data)
        {
            return md5(getBytesUtf8(data));
        }

        /**
         * Calculates the MD5 digest and returns the value as a 32 character hex string.
         * 
         * @param data
         *            Data to digest
         * @return MD5 digest as a hex string
         */
        public static String md5Hex(byte[] data)
        {
            return Hex.encodeHexString(md5(data));
        }

        /**
         * Calculates the MD5 digest and returns the value as a 32 character hex string.
         * 
         * @param data
         *            Data to digest
         * @return MD5 digest as a hex string
         * @throws IOException
         *             On error reading from the stream
         * @since 1.4
         */
        public static String md5Hex(java.io.InputStream data)
        {//throws IOException {
            return Hex.encodeHexString(md5(data));
        }

        /**
         * Calculates the MD5 digest and returns the value as a 32 character hex string.
         * 
         * @param data
         *            Data to digest
         * @return MD5 digest as a hex string
         */
        public static String md5Hex(String data)
        {
            return Hex.encodeHexString(md5(data));
        }

        /**
         * Calculates the SHA-1 digest and returns the value as a <code>byte[]</code>.
         * 
         * @param data
         *            Data to digest
         * @return SHA-1 digest
         */
        public static byte[] sha(byte[] data)
        {
            return getShaDigest().digest(data);
        }

        /**
         * Calculates the SHA-1 digest and returns the value as a <code>byte[]</code>.
         * 
         * @param data
         *            Data to digest
         * @return SHA-1 digest
         * @throws IOException
         *             On error reading from the stream
         * @since 1.4
         */
        public static byte[] sha(java.io.InputStream data)
        {// throws IOException {
            return digest(getShaDigest(), data);
        }

        /**
         * Calculates the SHA-1 digest and returns the value as a <code>byte[]</code>.
         * 
         * @param data
         *            Data to digest
         * @return SHA-1 digest
         */
        public static byte[] sha(String data)
        {
            return sha(getBytesUtf8(data));
        }

        /**
         * Calculates the SHA-256 digest and returns the value as a <code>byte[]</code>.
         * <p>
         * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
         * </p>
         * 
         * @param data
         *            Data to digest
         * @return SHA-256 digest
         * @since 1.4
         */
        public static byte[] sha256(byte[] data)
        {
            return getSha256Digest().digest(data);
        }

        /**
         * Calculates the SHA-256 digest and returns the value as a <code>byte[]</code>.
         * <p>
         * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
         * </p>
         * 
         * @param data
         *            Data to digest
         * @return SHA-256 digest
         * @throws IOException
         *             On error reading from the stream
         * @since 1.4
         */
        public static byte[] sha256(java.io.InputStream data)
        {// throws IOException {
            return digest(getSha256Digest(), data);
        }

        /**
         * Calculates the SHA-256 digest and returns the value as a <code>byte[]</code>.
         * <p>
         * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
         * </p>
         * 
         * @param data
         *            Data to digest
         * @return SHA-256 digest
         * @since 1.4
         */
        public static byte[] sha256(String data)
        {
            return sha256(getBytesUtf8(data));
        }

        /**
         * Calculates the SHA-256 digest and returns the value as a hex string.
         * <p>
         * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
         * </p>
         * 
         * @param data
         *            Data to digest
         * @return SHA-256 digest as a hex string
         * @since 1.4
         */
        public static String sha256Hex(byte[] data)
        {
            return Hex.encodeHexString(sha256(data));
        }

        /**
         * Calculates the SHA-256 digest and returns the value as a hex string.
         * <p>
         * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
         * </p>
         * 
         * @param data
         *            Data to digest
         * @return SHA-256 digest as a hex string
         * @throws IOException
         *             On error reading from the stream
         * @since 1.4
         */
        public static String sha256Hex(java.io.InputStream data)
        {// throws IOException {
            return Hex.encodeHexString(sha256(data));
        }

        /**
         * Calculates the SHA-256 digest and returns the value as a hex string.
         * <p>
         * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
         * </p>
         * 
         * @param data
         *            Data to digest
         * @return SHA-256 digest as a hex string
         * @since 1.4
         */
        public static String sha256Hex(String data)
        {
            return Hex.encodeHexString(sha256(data));
        }

        /**
         * Calculates the SHA-384 digest and returns the value as a <code>byte[]</code>.
         * <p>
         * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
         * </p>
         * 
         * @param data
         *            Data to digest
         * @return SHA-384 digest
         * @since 1.4
         */
        public static byte[] sha384(byte[] data)
        {
            return getSha384Digest().digest(data);
        }

        /**
         * Calculates the SHA-384 digest and returns the value as a <code>byte[]</code>.
         * <p>
         * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
         * </p>
         * 
         * @param data
         *            Data to digest
         * @return SHA-384 digest
         * @throws IOException
         *             On error reading from the stream
         * @since 1.4
         */
        public static byte[] sha384(java.io.InputStream data)
        {// throws IOException {
            return digest(getSha384Digest(), data);
        }

        /**
         * Calculates the SHA-384 digest and returns the value as a <code>byte[]</code>.
         * <p>
         * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
         * </p>
         * 
         * @param data
         *            Data to digest
         * @return SHA-384 digest
         * @since 1.4
         */
        public static byte[] sha384(String data)
        {
            return sha384(getBytesUtf8(data));
        }

        /**
         * Calculates the SHA-384 digest and returns the value as a hex string.
         * <p>
         * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
         * </p>
         * 
         * @param data
         *            Data to digest
         * @return SHA-384 digest as a hex string
         * @since 1.4
         */
        public static String sha384Hex(byte[] data)
        {
            return Hex.encodeHexString(sha384(data));
        }

        /**
         * Calculates the SHA-384 digest and returns the value as a hex string.
         * <p>
         * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
         * </p>
         * 
         * @param data
         *            Data to digest
         * @return SHA-384 digest as a hex string
         * @throws IOException
         *             On error reading from the stream
         * @since 1.4
         */
        public static String sha384Hex(java.io.InputStream data)
        {// throws IOException {
            return Hex.encodeHexString(sha384(data));
        }

        /**
         * Calculates the SHA-384 digest and returns the value as a hex string.
         * <p>
         * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
         * </p>
         * 
         * @param data
         *            Data to digest
         * @return SHA-384 digest as a hex string
         * @since 1.4
         */
        public static String sha384Hex(String data)
        {
            return Hex.encodeHexString(sha384(data));
        }

        /**
         * Calculates the SHA-512 digest and returns the value as a <code>byte[]</code>.
         * <p>
         * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
         * </p>
         * 
         * @param data
         *            Data to digest
         * @return SHA-512 digest
         * @since 1.4
         */
        public static byte[] sha512(byte[] data)
        {
            return getSha512Digest().digest(data);
        }

        /**
         * Calculates the SHA-512 digest and returns the value as a <code>byte[]</code>.
         * <p>
         * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
         * </p>
         * 
         * @param data
         *            Data to digest
         * @return SHA-512 digest
         * @throws IOException
         *             On error reading from the stream
         * @since 1.4
         */
        public static byte[] sha512(java.io.InputStream data)
        {// throws IOException {
            return digest(getSha512Digest(), data);
        }

        /**
         * Calculates the SHA-512 digest and returns the value as a <code>byte[]</code>.
         * <p>
         * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
         * </p>
         * 
         * @param data
         *            Data to digest
         * @return SHA-512 digest
         * @since 1.4
         */
        public static byte[] sha512(String data)
        {
            return sha512(getBytesUtf8(data));
        }

        /**
         * Calculates the SHA-512 digest and returns the value as a hex string.
         * <p>
         * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
         * </p>
         * 
         * @param data
         *            Data to digest
         * @return SHA-512 digest as a hex string
         * @since 1.4
         */
        public static String sha512Hex(byte[] data)
        {
            return Hex.encodeHexString(sha512(data));
        }

        /**
         * Calculates the SHA-512 digest and returns the value as a hex string.
         * <p>
         * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
         * </p>
         * 
         * @param data
         *            Data to digest
         * @return SHA-512 digest as a hex string
         * @throws IOException
         *             On error reading from the stream
         * @since 1.4
         */
        public static String sha512Hex(java.io.InputStream data)
        {// throws IOException {
            return Hex.encodeHexString(sha512(data));
        }

        /**
         * Calculates the SHA-512 digest and returns the value as a hex string.
         * <p>
         * Throws a <code>RuntimeException</code> on JRE versions prior to 1.4.0.
         * </p>
         * 
         * @param data
         *            Data to digest
         * @return SHA-512 digest as a hex string
         * @since 1.4
         */
        public static String sha512Hex(String data)
        {
            return Hex.encodeHexString(sha512(data));
        }

        /**
         * Calculates the SHA-1 digest and returns the value as a hex string.
         * 
         * @param data
         *            Data to digest
         * @return SHA-1 digest as a hex string
         */
        public static String shaHex(byte[] data)
        {
            return Hex.encodeHexString(sha(data));
        }

        /**
         * Calculates the SHA-1 digest and returns the value as a hex string.
         * 
         * @param data
         *            Data to digest
         * @return SHA-1 digest as a hex string
         * @throws IOException
         *             On error reading from the stream
         * @since 1.4
         */
        public static String shaHex(java.io.InputStream data)
        {// throws IOException {
            return Hex.encodeHexString(sha(data));
        }

        /**
         * Calculates the SHA-1 digest and returns the value as a hex string.
         * 
         * @param data
         *            Data to digest
         * @return SHA-1 digest as a hex string
         */
        public static String shaHex(String data)
        {
            return Hex.encodeHexString(sha(data));
        }
    }
}